Dynamic uplink and downlink configuration using flexible subframes

ABSTRACT

An apparatus and method for dynamically changing an uplink and downlink ratio configuration is disclosed herein. An evolved Node B (eNodeB) operating in a wireless communications network transmits a System Information Block Type 1 (SIB1) including first uplink and downlink ratio configuration information. The eNodeB also transmits in at least one downlink sub frame of a radio frame configured in the first uplink and downlink ratio configuration second uplink and downlink ratio configuration information. The second uplink and downlink ratio configuration information is included in a downlink control information (DCI) message. The DCI message is included in the at least one downlink subframe of the radio frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/589,774 entitled “Advanced Wireless Communication Systems andTechniques” filed on Jan. 23, 2012, the content of which is incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to wireless communications.More particularly, the present disclosure relates to changing uplink anddownlink ratio configurations within wireless communication systems.

BACKGROUND

In the current 3rd Generation Partnership Project (3GPP) long termevolution (LTE) time division duplex (TDD)-Advanced systems, the samefrequency bands are used for the uplink and downlink transmissionsbetween evolved-universal terrestrial radio access network (E-UTRAN)node Bs (eNodeBs) and user equipment (UE). Uplink and downlinktransmissions are separated by transmitting either uplink data ordownlink data at each pre-determined block of time, known as subframes,on the same frequency bands. In TDD deployment, the uplink and downlinktransmissions are structured into radio frames, each 10 ms in timelength. Each radio frame may comprise a single frame or two half-framesof each 5 ms in time length. Each half-frame, in turn, may comprise fivesubframes of 1 ms time length each. Particular designations of subframeswithin a radio frame for uplink or downlink transmission—referred to asuplink and downlink configurations—can be defined. The seven supporteduplink and downlink configurations (also referred to UL/DLconfigurations, uplink-downlink configurations, or uplink-downlink ratioconfigurations) are shown in a table 100 of FIG. 1, in which “D” denotesa sub frame reserved for downlink transmission, “U” denotes a subframereserved for uplink transmission, and “S” denotes a special sub framewhich includes the downlink pilot time slot (DwPTS), guard period (GP)and uplink pilot time slot (UpPTS) fields. (See 3GPP TS 36.211 Version10.5.0, E-UTRA Physical Channels and Modulation (Release 10), June2012.) In the currently supported uplink-downlink configurations,between 40 to 90% of the subframes within a given radio frame aredownlink subframes.

The EUTRAN decides which one of the supported uplink-downlinkconfigurations applies for a given eNodeB. Once the uplink-downlinkconfiguration has been allocated, this configuration is typically notchanged during normal operation of the cell or cells served by theeNodeB. This is the case even when uplink or downlink transmission loadsare mismatched to the current uplink-downlink configuration. Even if theuplink-downlink configuration for a given eNodeB is desirous of beingchanged, there is a minimum latency of 640 ms under the current standardto effect modification of the System Information Block Type 1 (SIB1)information—the mechanism by which the uplink-downlink configuration isallocated and re-allocated. Current 3GPP LTE-Advanced systems do notsupport dynamic adjustment of the uplink and downlink ratioconfigurations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates supported uplink-downlink ratio configurations underthe current 3GPP LIE TDD-Advanced standard.

FIG. 2 illustrates an example (portion) of a wireless communicationsnetwork shown in a homogenous network deployment according to someembodiments.

FIG. 3 illustrates an example block diagram showing details of theeNodeB included in the wireless communications network of FIG. 2according to some embodiments.

FIG. 4 illustrates an example (portion) of a wireless communicationnetwork shown in a heterogeneous network deployment according to someembodiments.

FIG. 5 illustrates a radio frame structure that supports UL/DLconfiguration allocation for legacy Release 8/9/10 UEs and alsofacilitates a dynamic UL/DL re-configuration indication mechanism forRelease 11 and later UEs according to some embodiments.

FIGS. 6A-6C illustrate an example flow diagram for dynamically adjustingthe UL/DL configuration by any eNodeB or BS included in the wirelesscommunications network of FIG. 2 or 4 according to some embodiments.

FIG. 6D illustrates an example flow diagram of operations performed by aUE in response to transmissions of UL/DL configuration allocationinformation by an eNodeB or BS according to some embodiments.

FIG. 7 lists the possible UL/DL re-configuration patterns correspondingto each of a given legacy UL/DL configuration according to someembodiments.

FIG. 8 illustrates an example implementation of the table of FIG. 7.

FIGS. 9A-9D illustrate embodiments of a new DCI format that includes theCIF value.

FIG. 10 lists the possible UL/DL re-configuration patterns correspondingto each of a given legacy UL/DL configuration according to anotherembodiment.

FIG. 11 illustrates the frame structures of new UL/DL configurationsincluded in the table of FIG. 10.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to create and use a computer system configuration and relatedmethod and article of manufacture to dynamically adjust theuplink-downlink configuration by any eNodeB within a wirelesscommunications network using an indication mechanism that does notinvolve modification of the System Information Block Type 1 (SIB1). Anew radio frame structure is defined that includes one or more flexiblesubframes. One or more of such flexible subframes is dynamicallyswitched from being an uplink subframe to a downlink subframe, or viceversa, within a radio frame time period. The new uplink-downlinkconfiguration defined by the dynamically switched flexible subframe(s)is identified using a configuration indication field (CIF) value. A newdownlink control information (DCI) format is defined to include the CIFvalue indicative of the new uplink-downlink configuration. The DCImessage including the CIF value is transmitted in the physical downlinkcontrol channel (PDCCH) region within the control region of the downlinksubframe(s). The CIF indication scheme is recognizable by Release 11 orlater user equipment (UEs) associated with the given eNodeB, while thelegacy UEs (e.g., Release 8/9/10 UEs) associated with the given eNodeBcontinue to operate according to the uplink-downlink configurationallocated using SIB1.

Various modifications to the embodiments will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments and applications without departing fromthe scope of the invention. Moreover, in the following description,numerous details are set forth for the purpose of explanation. However,one of ordinary skill in the art will realize that embodiments of theinvention may be practiced without the use of these specific details. Inother instances, well-known structures and processes are not shown inblock diagram form in order not to obscure the description of theembodiments of the invention with unnecessary detail. Thus, the presentdisclosure is not intended to be limited to the embodiments shown, butis to be accorded the widest scope consistent with the principles andfeatures disclosed herein.

The dynamic uplink-downlink (UL/DL) re-configuration mechanism describedherein is applicable in homogeneous and/or heterogeneous networkdeployments. Example homogenous and heterogeneous network deploymentsare illustrated respectively in FIGS. 2 and 4. FIG. 2 illustrates anexample (portion) of a wireless communications network 200 shown in ahomogenous network deployment according to some embodiments. In oneembodiment, the wireless communications network 200 comprises an evolveduniversal terrestrial radio access network (EUTRAN) using the 3rdGeneration Partnership Project (3GPP) long term evolution (LTE) standardand operating in time division duplexing (TDD) mode. The wirelesscommunications network 200 includes a first EUTRAN or evolved Node B(eNodeB or eNB) 202, a second eNodeB 206, and a plurality of userequipments (UEs) 216.

The first eNodeB 202 (also referred to as eNodeB1 or a first basestation) serves a certain geographic area, denoted as a first cell 204.The UEs 216 located within the first cell 204 are served by the firsteNodeB 202. The first eNodeB 202 communicates with the UEs 216 on afirst carrier frequency 212 (F1) and optionally, one or more secondarycarrier frequencies, such as a second carrier frequency 214 (F2).

The second eNodeB 206 is similar to the first eNodeB 202 except itserves a different cell from that of the first eNodeB 202. The secondeNodeB 206 (also referred to as eNodeB2 or a second base station) servesanother certain geographic area, denoted as a second cell 208. The UEs216 located within the second cell 208 are served by the second eNodeB206. The second eNodeB 206 communicates with the UEs 216 on the firstcarrier frequency 212 (F1) and optionally, one or more secondary carrierfrequencies, such as the second carrier frequency 214 (F2).

The first and second cells 204, 208 may or may not be immediatelyco-located next to each other. However, the first and second cells 204,208 are situated close enough to be considered neighboring cells, suchthat the user traffic pattern of one of the first or second eNodeB 202,206 is relevant to the other eNodeB. For example, one of the UE 216served by the first eNodeB 202 may move from the first cell 204 to thesecond cell 208, in which case a hand-off takes places from the firsteNodeB 202 to the second eNodeB 206 with respect to the particular UE316.

The UEs 216 may comprise a variety of devices that communicate withinthe wireless communications network 200 including, but not limited to,cellular telephones, smart phones, tablets, laptops, desktops, personalcomputers, servers, personal digital assistants (PDAs), web appliances,set-top box (STB), a network router, switch or bridge, and the like. TheUEs 216 can comprise Release 8, 9, 10, 11, and/or later UEs.

It is understood that the wireless communications network 200 includesmore than two eNodeBs. It is also understood that each of the first andsecond eNodeBs 202, 206 can have more than one neighboring eNodeB. As anexample, the first eNodeB 202 may have six or more neighboring eNodeBs.

In one embodiment, the UEs 216 located in respective first or secondcells 204, 208 transmits data to its respective first or second eNodeB202, 206 (uplink transmission) and receives data from its respectivefirst or second eNodeB 202, 206 (downlink transmission) using radioframes comprising Orthogonal Frequency-Division Multiple Access (OFDMA)frames configured for time division duplexing (TDD) operations. Each ofthe radio frames comprises a plurality of uplink and downlink subframes,the uplink and downlink subframes configured in accordance with theuplink-downlink ratio configuration selected from among the supporteduplink-downlink ratio configurations shown in FIG. 1. (See 3GPP TS36.211 Version 9.1.0, E-UTRA Physical Channels and Modulation (Release9), March 2010.)

FIG. 3 illustrates an example block diagram showing details of the firstand second eNodeBs 202, 206 and/or UEs 216 according to someembodiments. Each of the first and second eNodeBs 202, 206 (and/or UEs216) includes a processor 300, a memory 302, a transceiver 304,instructions 306, and other components (not shown). The first and secondeNodeB 202, 206 (and/or UEs 216) are similar to each other in hardware,firmware, software, configurations, and/or operating parameters.

The processor 300 (also referred to as processing circuitry) comprisesone or more central processing units (CPUs), graphics processing units(GPUs), or both. The processor 300 provides processing and controlfunctionalities for the first and second eNodeBs 202, 206 (and/or UEs216), respectively. Memory 302 comprises one or more transient andstatic memory units configured to store instructions and data for thefirst and second eNodeBs 202, 206 (and/or UEs 216), respectively. Thetransceiver 304 comprises one or more transceivers including amultiple-input and multiple-output (MIMO) antenna to support MIMOcommunications. The transceiver 304 receives uplink transmissions andtransmits downlink transmissions with the UEs 216, among other things,for the first and second eNodeBs 202, 206 (and/or UEs 216),respectively.

The instructions 306 comprises one or more sets of instructions orsoftware executed on a computing device (or machine) to cause suchcomputing device (or machine) to perform any of the methodologiesdiscussed herein. The instructions 306 (also referred to as computer- ormachine-executable instructions) may reside, completely or at leastpartially, within the processor 300 and/or the memory 302 duringexecution thereof by the first and second eNodeBs 202, 206 (and/or UEs216), respectively. The processor 300 and memory 302 also comprisemachine-readable media.

FIG. 4 illustrates an example (portion) of a wireless communicationnetwork 400 shown in a heterogeneous network deployment according tosome embodiments. In one embodiment, the wireless communications network400 comprises an EUTRAN using the 3GPP-LTE standard operating in TDDmode. The wireless communications network 400 includes a first eNodeB402, a second eNodeB 406, short range base stations (BSs) 420, 426, 440,446, and a plurality of user UEs 416, 424, 430, 444, 450.

The first eNodeB 402 (also referred to as eNodeB1, first base station,or first macro base station) serves a certain geographic area, denotedas a first macro cell 404. The UEs 416 located within the first macrocell 404 and associated with the first eNodeB 402 are served by thefirst eNodeB 402. The first eNodeB 402 communicates with the UEs 416 ona first carrier frequency 412 (F1) and optionally, one or more secondarycarrier frequencies, such as a secondary carrier frequency 414 (F2). Thefirst eNodeB 402, first macro cell 404, and UEs 416 are similar to thefirst eNodeB 202, first cell 204, and UEs 216, respectively.

The second eNodeB 406 is similar to the first eNodeB 402 except itserves a different cell from that of the first eNodeB 402. The secondeNodeB 406 (also referred to as eNodeB2, second base station, or secondmacro base station) serves another certain geographic area, denoted as asecond macro cell 408. The UEs 416 located within the second macro cell408 and associated with the second eNodeB 406 area served by the secondeNodeB 406. The second eNodeB 406 communicates with the UEs 416 on thefirst carrier frequency 412 (F1) and optionally, one or more secondarycarrier frequencies, such as the second carrier frequency 414 (F2). Thesecond eNodeB 406, second macro cell 408, and UEs 416 are similar to thesecond eNodeB 206, second cell 208, and UEs 416, respectively.

Located within the geographic area of the first macro cell 404 are oneor more short range BSs, such as short range BSs 420 and 426. The shortrange BS 420 serves a geographic area within the first macro cell 404,denoted as a short range cell 422. UEs 424 located within the shortrange cell 422 and associated with the short range BS 420 are served bythe short range BS 420. The short range BS 420 communicates with the UEs424 on one or more carrier frequencies. The short range BS 426 serves adifferent geographic area within the first macro cell 404, denoted as ashort range cell 428. UEs 430 located within the short range cell 428and associated with the short range BS 426 are served by the short rangeBS 426. The short range BS 426 communicates with the UEs 430 on adifferent carrier frequency than the first carrier frequency 412 (F1),and optionally, one or more secondary carrier frequencies that are alsodifferent from the second carrier frequency 414 (F2).

Located within the geographic area of the second macro cell 408 are oneor more short range BSs, such as short range BSs 440 and 446. The shortrange BS 440 serves a geographic area within the second macro cell 408,denoted as a short range cell 442. UEs 444 located within the shortrange cell 442 and associated with the short range BS 440 are served bythe short range BS 440. The short range BS 440 communicates with the UEs444 on a different carrier frequency than the first carrier frequency412 (F1), and optionally, one or more secondary carrier frequencies thatare also different from the second carrier frequency 414 (F2). The shortrange BS 446 serves a different geographic area within the second macrocell 408, denoted as a short range cell 448. UEs 450 located within theshort range cell 448 and associated with the short range BS 446 areserved by the short range BS 446. The short range BS 446 communicateswith the UEs 450 on a different carrier frequency than the first carrierfrequency 412 (F1), and optionally, one or more secondary carrierfrequencies that are also different from the second carrier frequency414 (F2).

Each of the short range cells 422, 428, 442, 448 comprises a femto cell,pico cell, or other cell defined by a base station—short, range BSs 420,426, 440, 446, respectively—operating at a significantly lower powerlevel and communication range in comparison to the base station of themacro cell in which it is located. The short, range BSs 420, 426, 440,446 may operate in accordance with commands from the its macro cell basestation, or it may be capable of independent operation.

The first and second macro cells 404, 408 may or may not be immediatelyco-located next to each other. However, the first and second macro cells404, 408 are situated close enough to be considered neighboring cells,such that the user traffic pattern of one of the first or second eNodeB402, 406 is relevant to the other eNodeB (and possibly the short rangeBSs within that eNodeB). Due to the proximity of the eNodeBs or BSs toeach other, there may be BS/eNodeB-to-BS/eNodeB interference and/orUE-to-UE interference.

Each of the first eNodeB 402, second eNodeB 406, short range BS 420,short range BS 426, short range BS 440, and short range BS 446 specifiesan uplink-downlink configuration from among the supporteduplink-downlink configurations (shown in FIG. 1) to its associated UEs.The selected uplink-downlink configurations can be the same or differentamong the first eNodeB 402, second eNodeB 406, short range BS 420, shortrange BS 426, short range BS 440, and short range BS 446 depending onpre-determined or current operating conditions. Each of the first eNodeB402, second eNodeB 406, short range BS 420, short range BS 426, shortrange BS 440, and short range BS 446 includes a processor, memory,transceiver, instructions, and other components described above inconnection with FIG. 3.

The UEs 416, 424, 430, 444, 450 may comprise a variety of devices thatcommunicate within the wireless communications network 400 including,but not limited to, cellular telephones, smart phones, tablets, laptops,desktops, personal computers, servers, personal digital assistants(PDAs), web appliances, set-top box (STB), a network router, switch orbridge, and the like. The UEs 416, 424, 430, 444, 450 can compriseRelease 8, 9, 10, 11, and/or later UEs. The UEs 416, 424, 430, 444, and450 can be similar to each other and to the UEs 216. The UEs 416, 424,430, 444, 450 transmit and receive data with its respective BS/eNodeB inaccordance with the uplink-downlink ratio configuration selected for thegiven BS/eNodeB. Although UEs 416, 424, 430, 444, 450 are shownassociated with a respective BS/eNodeB, it is understood that any of theUEs 416, 424, 430, 444, 450 can move in or out of a given cell toanother cell and be associated with a different BS/eNodeB.

It is understood that the wireless communications network 400 includesmore than two eNodeBs. It is also understood that each of the first andsecond eNodeBs 402, 406 can have more than one neighboring eNodeB. As anexample, the first eNodeB 402 may have six or more neighboring eNodeBs.It is further understood that any of the macro cells can include zero,one, two, or more short range cells within its area.

FIG. 5 illustrates a radio frame structure 500 that supports UL/DLconfiguration allocation for legacy Release 8/9/10 UEs (in accordancewith the supported UL/DL configurations shown in FIG. 1) and alsofacilitates a dynamic UL/DL re-configuration indication mechanism forRelease 11 and later UEs according to some embodiments. The radio framestructure 500 comprises ten subframes—denoted by subframe index 0through 9 from left to right. Subframes 0, 5, and 6 are designated asdownlink subframes: Subframe 1 is designated as a special subframe;Subframe 2 is designated as an uplink subframe; and Subframes 3, 4, 7,8, and 9 are designated as flexible subframes (FlexSFs). As described indetail below, the flexible subframes within the radio frame aredesignated for flexible transmission direction encoding—each of theflexible subframes can be dynamically designated a downlink or specialuplink subframe for Release 11 or later UEs. The special uplink subframeincludes a downlink transmission period to transmit downlink controlchannels, a central guard period (GP) to switch between a downlink anduplink transmission, and an uplink data transmission period. In TDD-LTEdeployment, the radio frame structure 500 is 10 ms in time length andeach sub frame within the radio frame structure 500 is 1 ms in timelength.

FIGS. 6A-6C illustrate an example flow diagram 600 for dynamicallyadjusting the UL/DL configuration for any eNodeB or BS included in thewireless communications network 200 or 400 according to someembodiments. Using the new radio frame structure 500 of FIG. 5, selectflexible subframes are designated to switch from a UL subframe to a DLsubframe, or vice versa, within a radio frame time period, therebydefining a new UL/DL configuration relative to the operating UL/DLconfiguration allocated via SIB1. The new UL/DL configuration isindicated using a new DCI message transmitted in the PDCCH. Thediscussion below is made with respect to first eNodeB 202 and UEs 216;however, it is understood that any BS or eNodeB within the wirelesscommunications network 200 or 400 (e.g., first eNodeB 202, second eNodeB206, first eNodeB 402, second eNodeB 406, short range BS 420, shortrange BS 426, short range BS 440, short range BS 446) can perform theprocess shown in flow diagram 600.

At a block 602, the first eNodeB 202 determines and transmits allocationof an (initial) UL/DL configuration ratio from among the supported UL/DLconfiguration ratios (see FIG. 1) via the SIB1 (or a system informationdata block). The SIB1 message is broadcast to all the UEs 216 within thefirst cell 204. Upon receipt of the SIB1 message, and included within itthe specification of a particular UL/DL configuration, by the UEs 216(e.g., the legacy Release 8/9/10 UEs and Release 11 or later UEs), theUEs know when to transmit data to the first eNodeB 202 and when toreceive data from the eNodeB 202. This UL/DL configuration allocation isalso referred to as the legacy UL/DL configuration or first UL/DLconfiguration.

Next at a block 604, the first eNodeB 202 monitors in real-time or nearreal-time traffic conditions associated with the UEs 216 within itsfirst cell 204, possible interference from other BSs or eNodeBs, andother parameters relevant to determining whether a UL/DLre-configuration is warranted. For instance, a number of UEs associatedwith the first eNodeB 202 may be requesting high definition (HD) moviesfrom online movie providers, thus creating a high downlink traffic loadfor the first cell 204. Such material change in the traffic load sincethe current UL/DL configuration was selected may benefit from changingto a different UL/DL configuration having more downlink subframes inorder to more effectively meet the downlink demands.

When the first eNodeB 202 determines that a UL/DL re-configuration isdesired, the first eNodeB 202 dynamically performs a UL/DLre-configuration in accordance with a UL/DL re-configuration mechanismat a block 606. Details of the UL/DL re-configuration mechanism orscheme are discussed in detail below with respect to FIGS. 6B and 6C.The UL/DL re-configuration comprises a UL/DL configuration differentfrom the UL/DL configuration allocated in block 602. The UL/DLre-configuration allocation is detectable by certain types of UEs withinthe first cell 204 (e.g., Release 11 or later UEs) but not by othertypes of UEs within the first cell 204 (e.g., Release 8/9/10 legacyUEs). For those UEs unable to detect the UL/DL re-configurationallocation, such UEs continue to operate in accordance with the UL/DLconfiguration allocation of block 602. The UL/DL re-configuration isconfigured to maintain backward compatibility for those UEs unable todetect and/or operate in accordance with the new allocation.

The legacy UEs are unaware of the UL/DL re-configuration due to, forexample, use of a new indication format not recognized by the legacyUEs. Thus the legacy UEs continue to operate in accordance with theUL/DL configuration allocation from block 602 while the Release 11 orlater UEs operate in accordance with the UL/DL re-configurationallocation from block 606. This may result in some performancedegradation for the legacy UEs, but the overall instantaneous trafficconditions within the first cell 204 are handled more effectively withthe UL/DL re-configuration than without.

Then at a block 608, an identifier of the dynamically re-configuredUL/DL allocation is transmitted (e.g., broadcast) by the first eNodeB202 to the UEs 216 within the first cell 204 (or at least those UEscapable of detecting the new allocation). The identification of thedynamically re-configured UL/DL allocation is specified in aconfiguration indication field (CIF) included in a downlink controlinformation (DCI) message, the DCI message being included in thePhysical Downlink Control Channel (PDCCH), and the PDCCH being includedin one or more downlink subframes of the radio frames configuredaccording to the existing UL/DL configuration (e.g., as set forth inblock 602). The DCI message also includes scheduling or hybrid automaticrepeat request (HARQ) timing information associated with the UL/DLre-configuration.

The first eNodeB 202 also monitors whether the UL/DL configuration(determined in block 602) should be changed at a block 610. Even if aUL/DL re-configuration has occurred, it may be beneficial to also updatethe UL/DL configuration via SIB1. For example, if there are mostlylegacy UEs within the first cell 204 and/or the increase in downlinkdemand is coming from the legacy UEs, a UL/DL re-configuration may notaddress the traffic load change since the legacy UEs don't recognize theUL/DL re-configuration. In other words, depending on the mix of UEswithin the first cell 204 or the particular traffic conditions, a globalchange to the UL/DL configuration that effects all the UEs within thefirst cell 204 can be implemented rather than the selective changeprovided by a UL/DL re-configuration.

If the UL/DL configuration is maintained as is (no branch of block 610),then the flow diagram 600 returns to block 604 to determine if a UL/DLre-configuration should occur. Otherwise if a UL/DL configuration changeis desired (yes branch of block 610), then the flow diagram 600 returnsto block 602 to determine and transmit a subsequent UL/DL configurationselected from among the supported UL/DL configurations via SIB1.

FIG. 6B illustrates sub-blocks of block 606 detailing dynamic UL/DLre-configuration according to one embodiment. At a sub-block 620, thefirst eNodeB 202 determines which flexible subframe(s) within the radioframe to change (or re-configure) from UL subframe(s) to DL subframe(s).In this embodiment, (1) one or more of the subframes within the radioframe of the legacy UL/DL configuration that is designated a flexiblesubframe according to the radio frame structure 500 (e.g., Subframes 3,4, 7, 8, and/or 9), and (2) which is designated as a UL subframe in thelegacy UL/DL configuration is a candidate to be dynamicallyre-configured to a DL subframe. The following design principles areimplemented to define dynamically re-configuring select flexiblesubframes into pre-defined patterns in a unidirectional mode:

-   -   One or more UL subframe in a radio frame of a legacy UL/DL        configuration (e.g., a supported configuration indicated by        SIB1) that is designated a flexible subframe (e.g., Subframe 3,        4, 7, 8, or 9) can be changed to a DL subframe. This ensures no        negative impact on the common reference signal (CRS)-based        measurement accuracy of legacy UEs.    -   And, the new UL/DL configuration corresponding to the UL        flexible subframe(s) changed to DL subframe(s) (also referred to        as the UL/DL re-configuration pattern, UL/DL re-configuration,        or a new UL/DL configuration of frame structure type 2 (FS2))        comprises a supported UL/DL configuration shown in FIG. 1. No        new UL/DL configuration patterns are generated due to the        dynamic reconfiguration, in order to avoid defining new hybrid        automatic repeat request (HARQ)-timing relationship for both        physical downlink shared channel (PDSCH) and physical uplink        shared channel (PUSCH) transmissions.

Based on these principles, up to three UL/DL re-configuration patternsare possible for a given legacy UL/DL configuration. Table 700 shown inFIG. 7 lists the possible UL/DL re-configuration patterns correspondingto each of a given legacy UL/DL configuration. Table 700 includes a row702 that provides the legacy UL/DL configurations—the UL/DLconfigurations specified via SIB1 to all the UEs (including theRel-8/9/10 UEs and Rel-11 or later UEs) in the first cell 204 by thefirst eNodeB 202 at the block 602. Below each legacy UL/DL configuration(e.g., each column in table 700) are the possible UL/DL re-configurationpatterns corresponding to the particular legacy UL/DL configuration. Theconfiguration numbers in table 700 correspond to the configurationnumbers in the leftmost column of table 100 in FIG. 1. “R” denotes beingreserved for future use. Table 700 also includes a column 704 providingtwo-bit configuration indication field (CIF) values to define or signalthe particular UL/DL re-configuration for a given legacy UL/DLconfiguration. Note that based on the above principles, none of thesupported UL/DL re-configuration patterns in table 700 is a new UL/DLconfiguration—none are outside the existing supported UL/DLconfigurations defined in FIG. 1. Also note that all of the supportedUL/DL re-configuration patterns are limited to UL/DL configurations withthe same number of switch points (between DL/UL or UL/DL). This reducesthe control overhead needed for signaling the latest configurationrecognizable by Rel-11 or later UEs.

With knowledge of the current legacy UL/DL configuration (from block602), the first eNodeB 202 selects a UL/DL re-configuration from amongthe supported UL/DL re-configurations corresponding to the currentlegacy UL/DL configuration in table 700. The first eNodeB 202 determinesa particular one of the UL/DL re-configuration patterns based on thetraffic condition requirements. Once the particular one of the UL/DLre-configuration is selected in light of the current legacy UL/DLconfiguration, the first eNodeB 202 obtains the CIF value correspondingto the selected UL/DL re-configuration from table 700 (block 622).

An example visual implementation of blocks 620 and 622 is illustrated inFIG. 8. In FIG. 8, the legacy UL/DL configuration indicated by SIB1 isConfiguration 1, denoted as UL/DL configuration 802. The UL/DLconfiguration 802 (Configuration 1) is defined as CIF value “00” intable 700. According to table 700, the UL/DL re-configurations supportedfor UL/DL configuration 802 (Configuration 1) are: Configuration 2,Configuration 5, or Reserved. Thus, the first eNodeB 202 can dynamicallyre-configure UL/DL configuration 802 (Configuration 1) to either UL/DLre-configuration 804 (Configuration 2) or UL/DL re-configuration 806(Configuration 5). If UL/DL re-configuration 804 (Configuration 2) isselected, then the corresponding OF value is “01.” If UL/DLre-configuration 806 (Configuration 5) is selected, then thecorresponding CIF value is “10.”

In some embodiments, in order to further achieve reduction in UL/DLre-configuration signaling requirements, the CIF value may be designatedas a 1-bit value (“0” or “1”). In this case the number of possible UL/DLre-configurations is reduced from that shown in table 700. A givenlegacy UL/DL configuration can be defined as having a CIF value “0” andit may have a single supported UL/DL re-configuration having a CIF value“1.” For example, instead of legacy UL/DL configuration 802(Configuration 1) having two UL/DL re-configuration possibilities, itmay be restricted to just UL/DL re-configuration 804 (Configuration 2).

Next at a block 624, the first eNodeB 202 generates a downlink controlinformation (DCI) message including the CIF value determined in block622. (The CIF value is also referred to as a CIF indictor, CIF signal,or UL/DL re-configuration identifier.) A new DCI format is used for CIFtransmission. In one embodiment each downlink subframes of the currentUL/DL configuration includes the new DCI message. In another embodiment,a pre-defined subset of the downlink subframes of the current UL/DLconfiguration includes the new DCI message. To support this new DCIformat, a new radio network temporary identifier (RNTI) value, named“CI-RNTI,” is defined to identify the new DCI format and is used toscramble the cyclic redundancy check (CRC) parity bits of the new DCIformat. The new DCI message is included in the common search space (CSS)of the PDCCH region in the downlink subframe(s). Alternatively the newDCI message is UE specific, and is transmitted on UE-specific searchspace (USS) of the PDCCH region in the downlink subframe(s). For the UEspecific case the CRC parity bits are scrambled in accordance with anUE-specific RNTI (C-RNTI).

FIGS. 9A and 9B illustrate one embodiment of the new DCI format thatincludes the CIF value respectively for a single common carrier (CC) anda multiple CC scenario. In FIG. 9A, a DCI format 900 for single CCsupporting UL/DL re-configuration comprises—from left to rightmostbits—a CIF value field 902, a reserved field 904, and a CRC with CI-RNTIscrambling field 906. The data size of DCI format 900 is the same as forDCI format 1C in the current technical specification. (See 3GPP TS36.212 Version 10.6.0, E-UTRA Multiplexing and Channel Coding (Release10), July 2012.) The CIF value field 902 comprises a 2-bit field, a1-bit field, or other bit size in accordance with the CIF valuesidentifying the supported UL/DL re-configurations. The CRC with CI-RNTIscrambling field 906 comprises a 16-bit field.

FIG. 9B illustrates a DCI format 910 for multiple CCs comprising—fromleft to rightmost bits—a CIF value field for each of the multiple CCsthat support UL/DL re-configuration (e.g., a CIF value field associatedwith a first CC (CC0) 912, a CIF value field associated with a second CC(CC1) 914, a CIF value field associated with a third CC (CC2) 916, a CIFvalue field associated with a fourth CC (CC3) 918, a CIF value fieldassociated with a fifth CC (CC4) 920), a reserved field 922, and a CRCwith CI-RNTI scrambling field 924. The data size of DCI format 910 isthe same as for DCI format 1C in the current technical specification.(See 3GPP TS 36.212 Version 10.6.0, E-UTRA Multiplexing and ChannelCoding (Release 10), July 2012.) Each of the CIF value fields 912, 914,916, 918, 920 comprises a 2-bit field, a 1-bit field, or other bit sizein accordance with the CIF values identifying the supported UL/DLre-configurations. The CRC with CI-RNTI scrambling field 924 comprises a16-bit field.

FIGS. 9C and 9D illustrate another embodiment of the new DCI format thatincludes the CIF value respectively for a single CC and a multiple CCscenario. The DCI message configured in the new DCI format istransmitted in the UE-specific search space of the PDCCH region of thedownlink subframes. In FIG. 9C, a DCI format 930 for single CCsupporting UL/DL re-configuration comprises a CIF value field 932 and aconventional DCI format field 934. The CIF value field 932 pads orappends the existing DCI format used for Rel-8/9/10 UEs, such as DCIformat 1, 1A, 2, or 2A. The CIF value field 932 comprises a 2-bit field,a 1-bit field, or other bit size in accordance with the CIF valuesidentifying the supported UL/DL re-configurations.

FIG. 9D illustrates a DCI format 940 for multiple CCs comprising a CIFvalue field for each of the multiple CCs that support UL/DLre-configuration (e.g., a CIF value field associated with a first CC(CC0) 942, a CIF value field associated with a second CC (CC1) 944, aCIF value field associated with a third CC (CC2) 946, a CIF value fieldassociated with a fourth CC (CC3) 948, a CIF value field associated witha fifth CC (CC4) 950) and a conventional DCI format field 952. The CIFvalue fields 942-950 pads or appends the existing DCI format used forRel-8/9/10 UEs, such as DCI format 1, 1A, 2, or 2A. Each of the CIFvalue fields 942-950 comprises a 2-bit field, a 1-bit field, or otherbit size in accordance with the CIF values identifying the supportedUL/DL re-configurations.

FIG. 6C illustrates sub-blocks of block 606 detailing dynamic UL/DLre-configuration according to an alternate embodiment. At a sub-block630, the first eNodeB 202 determines which flexible subframe(s) withinthe radio frame to change (or re-configure) from UL subframe(s) to DLsubframe(s) and/or from DL subframe(s) to UL subframe(s). In thisembodiment, one or more of the subframes within the radio frame of thelegacy UL/DL configuration that is designated a flexible subframeaccording to the radio frame structure 500 (e.g., Subframes 3, 4, 7, 8,and/or 9) is a candidate to be dynamically re-configured to a ULsubframe or a DL subframe. The following design principles areimplemented to define dynamically re-configuring select flexiblesubframes into pre-defined patterns in a bidirectional mode:

-   -   One or more of the subframes in a radio frame of a legacy UL/DL        configuration (e.g., a supported configuration indicated by        SIB1) that are designated as a flexible subframe (e.g., Subframe        3, 4, 7, 8, or 9) can be changed from a UL to DL subframe or        from DL to UL subframe. This ensures no negative impact on the        CRS-based measurement accuracy of legacy UEs.    -   For DL flexible subframes dynamically switched to a UL subframe,        the control region of the subframe remains unchanged as a DL        control region to maintain measurement accuracy and backward        compatibility with Rel-8/9/10 UEs (even though the data region        of such subframe has been switched to a UL data region).

Based on these principles, up to three UL/DL re-configuration patternsare possible for a given legacy UL/DL configuration. Table 1000 shown inFIG. 10 lists the possible UL/DL re-configuration patterns correspondingto each of a given legacy UL/DL configuration. Table 1000 comprises theUL/DL re-configuration patterns defined in table 700 and extends toinclude UL/DL re-configuration patterns that are different and new fromthe seven supported UL/DL configurations under the current technicalspecification. The layout of table 1000 is similar to that of table 700.

Table 1000 includes a row 1002 that provides the legacy UL/DLconfigurations that are specified via SIB1 to all the UEs (including theRel-8/9/10 UEs and Rel-11 or later UEs) in the first cell 204 by thefirst eNodeB 202 at the block 602. Below each legacy UL/DL configuration(e.g., each column in table 1000) are the possible UL/DLre-configuration patterns corresponding to that particular legacy UL/DLconfiguration. The configuration numbers in table 1000 correspond to theconfiguration numbers in the leftmost column of table 100 in FIG. 1. “R”denotes being reserved for future use. Table 1000 also includes a column1004 providing two-bit CIF values to define or signal the particularUL/DL re-configuration for a given legacy UL/DL configuration. Note thatall of the supported UL/DL re-configuration patterns are limited toUL/DL configurations with the same number of switch points (betweenDL/UL or UL/DL). This reduces the control overhead needed for signalingthe latest configuration recognizable by Rel-11 or later UEs. Theconfigurations within table 1000 marked with “*” or “**” are new UL/DLconfigurations relative to the current technical specification. FIG. 11illustrates the frame structures of these new UL/DL configurations. Thesubframes marked “F” in FIG. 11 are DL (flexible) subframes that weredynamically switched using CIF to special UL subframes.

With knowledge of the current legacy UL/DL configuration (from block602), the first eNodeB 202 selects a UL/DL re-configuration from amongthe supported UL/DL re-configurations corresponding to the currentlegacy UL/DL configuration in table 1000. The first eNodeB 202determines a particular one of the UL/DL re-configuration patterns basedon the traffic condition requirements. Once the particular one of theUL/DL re-configuration is selected in light of the current legacy UL/DLconfiguration, the first eNodeB 202 obtains the CIF value correspondingto the selected UL/DL re-configuration from table 1000 (block 632).

In some embodiments, in order to further achieve reduction in UL/DLre-configuration signaling requirements, the CIF value may be designatedas a 1-bit value (“0” or “1”). In this case the number of possible UL/DLre-configurations for a given legacy UL/DL configuration is reduced fromthat shown in table 1000. A given legacy UL/DL configuration can bedefined as having a CIF value “0” and it may have a single supportedUL/DL re-configuration having a CIF value “1.”

Next at a block 634, the first eNodeB 202 generates a DCI messageincluding the CIF value determined in block 632. A new DCI format isused for CIF transmission. The new DCI message is included in the CSS ofthe PDCCH region in the downlink subframes and/or control regions ofuplink subframes that were dynamically switched from downlink subframes.In one embodiment each downlink subframes of the current UL/DLconfiguration includes the new DCI message. In another embodiment, apre-defined subset of the downlink subframes of the current UL/DLconfiguration includes the new DCI message. To support this new DCIformat, a new RNTI value, named “CI-RNTI,” is defined to identify thenew DCI format and is used to scramble the cyclic redundancy check (CRC)parity bits of the new DCI format. The same DCI formats discussed abovewith respect to FIGS. 9A-9D can be used, with the appropriate CIF valuesdefined in table 1000, to generate the DCI message.

FIG. 6D illustrates an example flow diagram 650 of operations performedby a UE in response to transmissions of UL/DL configuration allocationinformation by an eNodeB or BS according to some embodiments. At a block652, a UE receives SIB1 information transmitted by the eNodeB associatedwith the UE. The SIB1 specifies a UL/DL configuration allocationselected from among the supported UL/DL configurations, as describedabove with respect to block 602 of FIG. 6A. In response, the UE switchesto the UL/DL configuration specified in SIB1 and going forwardcommunicates with the eNodeB according to that configuration (block654).

While operating in the currently specified UL/DL configuration, the UEblind decodes each received downlink subframe unless instructedotherwise at a block 656. For example, if dynamic UL/DL re-configurationallocation is configured to be transmitted in uplink subframe(s), thenthe UE is correspondingly configured to blind decode one or more uplinksubframes to detect a possible re-configuration allocation. Based on theblind decoded information, certain UEs can detect whether a dynamicUL/DL re-configuration allocation has been specified. The UE receivesthe transmission of the UL/DL re-configuration indication from theeNodeB, as described above with respect to block 608 of FIG. 6A. If theCIF value is recognized by the UE, then the UE can determine whether andwhich re-configuration allocation has been specified by the eNodeB. TheUE can be a type of UE capable of detecting changes in the UL/DLconfiguration via a specification scheme other than SIB1, such asRelease 11 or later UEs.

If the UE is capable of detecting dynamic re-configurations and are-configuration allocation is detected (yes branch of block 658), thenthe UE switches to the specified re-configuration allocation (from theSIB1 specified configuration) and then proceeds to operate in accordancewith the UL/DL re-configuration, including following the scheduling orHARQ timing provided in the downlink subframe(s). Because the eNodeB canalso transmit a new SIB1 that specifies a certain UL/DL configuration,the UE checks for such a new SIB1 at a block 662 after switching to thenon-SIB1 specified configuration at the block 660.

If the UE is not capable of detecting dynamic re-configurations (e.g., aRelease 8/9/10 legacy UE or a malfunctioning Release 11 or later UE) orno re-configuration is specified (no branch of block 658), then a checkfor a different UL/DL configuration specified via a new SIB1 isperformed at the block 662. If there is no such specification (no branchof block 662), then the UE continues to blind decode the downlinksubframes at the block 656. Otherwise the new SIB1 received by the UEprovides for a different UL/DL configuration (yes branch of block 662),and the UE switches to that UL/DL configuration at a block 664.

Flow diagram 650 can be performed by each UE associated with a giveneNodeB within the wireless communications network.

With both unidirectional and bidirectional dynamic re-configuration, theRel-11 or later UEs associated with the first eNodeB 202 detect thelatest UL/DL configuration dynamically (e.g., from radio frame to radioframe) via CIF signaling and accordingly follow the HARQ-ACK timing ofthe new configuration. The Rel-8/9/10 UEs are unable to detect thischange in the UL/DL configuration and continue to operate according tothe UL/DL configuration allocation transmitted through the SIB1. Thefirst eNodeB 202 is operable to properly schedule data transmission ofRel-8/9/10 UEs and makes sure that the corresponding PUSCH resources andHARQ-ACK resources of PDSCH and PUSCH (and other Rel-8/9/10 measurementaccuracy requirements defined in 3GPP TS 36.101 Version 10.4.0, E-UTRAUser Equipment (UE) Radio Transmission and Reception (Release 10),November 2011) are still valid even when certain of the flexiblesubframes are dynamically changed for the new release UEs.

Accordingly, an encoding scheme for dynamically adjusting the UL/DLconfiguration in a LTE-TDD network is disclosed. Each eNodeB transmits afirst UL/DL configuration allocation in a SIB1 message for each carrierfrequency served by that eNodeB. The first UL/DL configuration comprisesthe operating UL/DL configuration for all UEs associated with theeNodeB, including Rel-8/9/10 UEs and Rel-11 or later UEs. When theeNodeB determines that the current traffic load is inadequately handledby the first UL/DL configuration, the eNodeB dynamically adjusts thefirst UL/DL configuration to a second UL/DL configuration (also referredto as a UL/DL re-configuration). The second UL/DL configurationallocation is transmitted to the UEs in a DCI message mapped to thePDCCH. The second UL/DL configuration is detected by the Rel-11 andlater UEs, and such UEs change communication with the eNodeBaccordingly. The second UL/DL configuration is not detectable by legacyUEs, such as Rel-8/9/10 UEs. The legacy UEs continue to operate inaccordance with the first UL/DL configuration. The second UL/DLconfiguration is thus designed to maintain backward compatibility withlegacy UEs, minimize control overhead, satisfy instantaneous trafficsituation requirements, and reduce configuration change latency from aminimum of approximately 640 ms to less than 640 ms, such asapproximately 10 ms, less than 10 ms, or a radio frame time period.

The term “machine-readable medium,” “computer readable medium,” and thelike should be taken to include a single medium or multiple media (e.g.,a centralized or distributed database, and/or associated caches andservers) that store the one or more sets of instructions. The term“machine-readable medium” shall also be taken to include any medium thatis capable of storing, encoding or carrying a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies of the present disclosure. The term“machine-readable medium” shall accordingly be taken to include, but notbe limited to, solid-state memories, optical and magnetic media, andcarrier wave signals.

It will be appreciated that, for clarity purposes, the above descriptiondescribes some embodiments with reference to different functional unitsor processors. However, it will be apparent that any suitabledistribution of functionality between different functional units,processors or domains may be used without detracting from embodiments ofthe invention. For example, functionality illustrated to be performed byseparate processors or controllers may be performed by the sameprocessor or controller. Hence, references to specific functional unitsare only to be seen as references to suitable means for providing thedescribed functionality, rather than indicative of a strict logical orphysical structure or organization.

Although the present invention has been described in connection withsome embodiments, it is not intended to be limited to the specific formset forth herein. One skilled in the art would recognize that variousfeatures of the described embodiments may be combined in accordance withthe invention. Moreover, it will be appreciated that variousmodifications and alterations may be made by those skilled in the artwithout departing from the scope of the invention.

The Abstract of the Disclosure is provided to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

What is claimed is:
 1. A non-transitory computer readable medium comprising instructions that, when executed by one or more processors of a user equipment (UE), configure the LIE to perform operations for dynamically changing an uplink and downlink frame structure configuration, the operations comprising: transmitting, by an evolved Node B (eNodeB), a System Information Block Type 1 (SIB1) including first uplink and downlink subframe configuration information; and transmitting, by the eNodeB, in at least one downlink subframe of a radio frame configured in the first uplink and downlink subframe configuration, second uplink and downlink subframe configuration information, the second uplink and downlink subframe configuration information included in a downlink control information (DCI) message and the DCI message being included in the at least one downlink subframe of the radio frame for dynamically changing the uplink and downlink frame structure configuration from the first uplink and downlink subframe configuration information of the SIB1 to the second uplink and downlink subframe configuration of the DCI message.
 2. The non-transitory computer readable medium of claim 1, wherein the DCI message is included in each downlink subframe of the radio frame configured in the first uplink and downlink subframe configuration or a pre-defined subset of the downlink subframes of the radio frame configured in the first uplink and downlink subframe configuration.
 3. The non-transitory computer readable medium of claim 1, wherein the DCI message includes one or more uplink/downlink configuration indication values specifying the second uplink and downlink subframe configuration for each of respective one or more component carriers associated with the eNodeB.
 4. The non-transitory computer readable medium of claim 3, wherein a CIF value comprises a 2-bit value to specify up to four different uplink and downlink subframe configurations.
 5. The non-transitory computer readable medium of claim 3, wherein the CIF value comprises a 1-bit value to specify up to two different uplink and downlink subframe configurations.
 6. The non-transitory computer readable medium of claim 1, wherein the DCI message includes cyclic redundancy check (CRC) parity bits that are scrambled in accordance with a radio network temporary identifier (RNTI) identifying DCI messages configured to allocate the second uplink and downlink subframe configuration, and wherein the RNTI is configured to fix identify for broadcast of the second uplink and downlink subframe configuration, the RNTI known a priori to user equipment (UEs).
 7. The non-transitory computer readable medium of claim 1, wherein the DCI message is included in a common search space (CSS) of a physical downlink control channel (PDCCH) included in the at least one downlink subframe of the radio frame configured in the first uplink and downlink subframe configuration, and wherein a size of the DCI message is extended by padding bits to be a same size as one of DCI formats of a 3rd Generation Partnership Project (3GPP) long term evolution (LTE) Release 8/9/10 network.
 8. The non-transitory computer readable medium of claim 1, wherein the DCI message is included in a user equipment (UE)-specific search space (USS) of a physical downlink control channel (PDCCH) included in the at least one downlink subframe of the radio frame configured in the first uplink and downlink subframe configuration.
 9. The non-transitory computer readable medium of claim 1, wherein the eNodeB is configured to operate in accordance with a 3rd Generation Partnership Project (3GPP) long term evolution (LTE) network, and the radio frame comprises an orthogonal frequency-division multiple access (OFDMA) frame configured for time division duplex (TDD) operation.
 10. The non-transitory computer readable medium of claim 1 wherein the operations further comprise: initiating transmission, by the eNodeB, within a radio frame time period of transmission of the at least one downlink subframe, a second subframe configured in the second uplink and downlink subframe configuration.
 11. An apparatus of a user equipment (LTE) operating in a wireless communications network and configured for dynamic uplink and downlink configuration of a frame structure, the apparatus comprising: circuitry to receive a system information data block comprising a System information Block Type 1 including a first uplink and downlink configuration from a base station and to subsequently receive in at least one downlink subframe of a radio frame configured in the first uplink and downlink configuration, second uplink and downlink configuration information provided in a downlink control information (DCI) format; and processing circuitry to blind decode each received downlink subframe, including the at least one downlink subframe, to detect the second uplink and downlink configuration information and to initiate a dynamic changing of the uplink and downlink frame structure configuration from the first uplink and downlink subframe configuration of the S1131 to the second uplink and downlink subframe configuration of the DCI message.
 12. The apparatus of claim 11, wherein the wireless communications network in which the UE operates comprises a 3rd Generation Partnership Project (3GPP) long term evolution (LTE) network.
 13. The apparatus of claim 11, wherein the DCI format is included in a common search space (CSS) of a physical downlink control channel (PDCCH) included in the at least one downlink subframe of the radio frame configured in the first uplink and downlink configuration.
 14. The apparatus of claim 11, wherein the DCI message is included in a user equipment (UE)-specific search space (USS) of a physical downlink control channel (PDCCH) included in the at least one downlink subframe of the radio frame configured in the first uplink and downlink configuration.
 15. The apparatus of claim 11, wherein the UE switches from the first uplink and downlink configuration to the second uplink and downlink configuration in response to detecting the DCI format indicating the second uplink and downlink configuration.
 16. The apparatus of claim 11, wherein the processing circuitry maintains operating the UE in the first uplink and downlink configuration in response to an inability to recognize the DCI format indicating the second uplink and downlink configuration.
 17. The apparatus of claim 11, wherein a particular radio frame structure of the second uplink and downlink configuration is specified by a configuration number included in the DCI format.
 18. The apparatus of claim 17, wherein each of the first and second uplink and downlink configurations has a radio frame structure comprising ten subframes, each of the ten subframes designated as a special subframe (S), an uplink subframe (U), a downlink subframe (D), or a flexible subframe (F).
 19. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUUUDSUUU and the radio frame structure of the second uplink and downlink configuration comprises DSUUDDSUUD, DSUDDDSUDD, or DSUDDDDDDD, each of the radio frame structures being associated with a different CIF value from each other.
 20. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUUUDSUUD and the radio frame structure of the second uplink and downlink configuration comprises DSUUDDSUUD, DSUDDDSUDD, or DSUDDDDDDD, each of the radio frame structures being associated with a different CIF value from each other.
 21. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUUDDSUUD and the radio frame structure of the second uplink and downlink configuration comprises DSUDDDSUDD, DSUDDDDDDD, or DSUUFDSUUF, each of the radio frame structures being associated with a different CIF value from each other.
 22. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUDDDSUDD and the radio frame structure of the second uplink and downlink configuration comprises DSUDDDDDDD, DSUFDDSUFD, or DSUFFDSUFF, each of the radio frame structures being associated with a different CIF value from each other.
 23. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUDDDDDDD and the radio frame structure of the second uplink and downlink configuration comprises DSUUDDDDDD or DSUDDDDDDD, each of the radio frame structures being associated with a different CIF value from each other.
 24. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUUDDDDDD and the radio frame structure of the second uplink and downlink configuration comprises DSUDDDDDDD or DSUUFDDDDD, each of the radio frame structures being associated with a different CIF value from each other.
 25. The apparatus of claim 18, wherein the radio frame structure of the first uplink and downlink configuration comprises DSUDDDDDDD and the radio frame structure of the second uplink and downlink configuration comprises DSUFDDDDDD or DSUFFDDDDD, each of the radio frame structures being associated with a different CIF value from each other. 